Darth Queron was a mandalorian Sith Lord who served Rovaniss' Sith Empire. Queren was discovered to be Force talented by a group of FOrce sensitive beings at a young age who took him and began to train him until he killed them all. It was then that Queren learned of his past and that he was related to the ancient Sith Lord Darth Sethron who had risen to help Darth Zealot in the civil war between Levid and Zealot.
When Queren learned of Sethron's death at the hands of Soru's Jedi Order he found Rovaniss' Sith Empire and eagerly joined the fight against the Jedi.